The present disclosure herein relates to a material for an organic electroluminescent device and an organic electroluminescent device utilizing the same. More particularly, the present disclosure herein relates to a material for an organic electroluminescence device having high emission efficiency when utilized in a layer between an emission layer and an anode, and an organic electroluminescence device utilizing the same.
In recent years, organic electroluminescent (EL) displays is one type of image displays that have been actively developed. Unlike a liquid crystal display and the like, the organic EL display is a so-called self-luminescent display which performs display by emitting light from a luminescent material (including an organic compound) in its emission layer through the recombination of holes and electrons injected from an anode and a cathode in the emission layer.
An example of an organic electroluminescence device (organic EL device) known in the art is an organic EL device which includes an anode, a hole transport layer disposed on the anode, an emission layer disposed on the hole transport layer, an electron transport layer disposed on the emission layer, and a cathode disposed on the electron transport layer. Holes injected from the anode are injected into the emission layer via the hole transport layer. Meanwhile, electrons are injected from the cathode, and then injected via the electron transport layer into the emission layer. The holes and the electrons injected into the emission layer are recombined to generate excitons within the emission layer. The organic EL device emits light by radiation deactivation of the excitons. Also, the organic EL device is not limited to the above-described configuration but may be changed in various suitable forms.
In the application of the organic EL device in a display apparatus, the high efficiency of the organic EL device is required. To realize the high efficiency of the organic EL device, the normalization and the stabilization of a hole transport layer have been examined. As a hole transport material utilized in a hole transport layer, a compound including carbazole or amine, and a compound obtained by combining thereof (e.g., a compound including both the carbazole group and the amine group) and having dibenzofuran and amine (e.g., a compound including both the dibenzofuran group and the amine group) may be utilized. For example, an amine compound including fluorene and dibenzofuran or an amine compound having a terphenyl group and dibenzofuran is generally utilized. However, since the compound including a terphenyl group or a fluorene ring structure is thermally decomposed by high temperature during the deposition process, it is undesirable in consideration of the manufacturing process. In addition, these compounds have high electron transport properties, and in the case that the compounds are applied in an electron blocking layer, the emission efficiency of an organic EL device may not be sufficiently improved.
As the hole transport material, a polyamine compound having dibenzofuran and (e.g., combined with) two or more amine parts (e.g., groups), an amine compound having carbazole and dibenzofuran, etc. may be utilized. In addition, a dibenzofuran derivative, an anthracene derivative having dibenzofuran and amine as substituents, a compound including an amino group making a direct linkage with dibenzofuran, dibenzofuran including a substituent having amine at position 2, a structure obtained by connecting 3-dibenzofuran group-phenyl group-amine, etc. may be utilized. Further, an amine derivative including a deuterated phenyl group, a monoamine material including diphenyl or triphenylated phenyl and dibenzofuran, etc. may be utilized. In addition, a monoamine material including a plurality of dibenzofuran combined at position 3 or a monoamine material including one dibenzofuran combined at a position other than 3 as the host of an emission layer of an organic EL device including a plurality of emission layers may be utilized. Meanwhile, a monoamine material including carbazole and dibenzofuran combined at position 3 may be utilized, and the combination of an amine material including dibenzofuran with a specific device structure may be utilized.
However, it may be difficult for an organic EL device utilizing these materials to have sufficient emission efficiency and emission life, and an organic EL device having higher emission efficiency is required as of now.